1. Field of the Invention
This invention relates to a device for vacuum attachment of an object to a surface, such a skin area, especially a device in the form of a suction electrode assembly. More particularly the present invention relates to a suction electrode assembly for use in taking electrocardiograms and in carrying out other biophysical examinations and treatments.
A vacuum attachment device of the kind contemplated here is a device which is adapted to be held to a surface under the action of a negative pressure in a vacuum chamber or vacuum cup which is partly delimited by the surface. More particularly, the negative pressure is applied to the vacuum chamber by a vacuum source, such as a suction pump, which is connected to the device.
2. Description of the Related Art
Devices of this kind are embodied in, for example, suction electrode assemblies for use in electrocardiographic and other biophysical examinations in which the surface to which the suction electrode assembly is held is an area of the skin of a patient or other individual. A requirement then to be met is that an electrode which forms part of the electrode assembly is held in good electrical contact with the surface.
Many different embodiments of suction electrode assemblies are known. Examples of embodiments are disclosed in EP-B-0143761, U.S. Pat. No. 4,248,243, DE-A-2548805, AT-C-248608, CH-A-301242.
It is desirable for hygienic and other reasons that it is easy to replace those parts of the electrode assembly which in use of the assembly contact the skin. Such parts can become contaminated by sweat and other skin secretions or by the medium (electrolytic gel) which is used to improve the electrical contact between the electrode and the skin.
Because of the negative pressure and capillary forces, there is a strong tendency for the contaminants to undesirably penetrate into certain regions of the electrode assembly. Those regions include where the assembly is connected with the vacuum source and with the electrical lead connecting the electrode with the electrical measuring equipment. The contaminants also promote the growth of microorganisms.
In practice, a replacement of the entire electrode device after each examination is not practical, because an electrode device which is adapted to be attached by vacuum is rather expensive. This is true especially when the electrode device includes a valve between the vacuum port and the vacuum chamber. This valve serves to disconnect the vacuum chamber from the vacuum port when the electrode device is not applied to the skin.
In practice, therefore, the replacement in the first instance must be limited to components which can be supplied at a sufficiently low cost and are most likely to become contaminated. That is, replaced parts preferably include at least those components which are in direct contact with the skin and are therefore unavoidably contaminated in use. Naturally, these components include the electrode and the sealing skirt or the like which delimits the area of the skin subjected to the negative pressure.
For that reason, the electrode device has to be constructed such that there is little likelihood of contaminants reaching those parts of the electrode device which are not replaced after each use, so that the electrode device can be used many times before it is necessary to replace or clean those parts which are not replaced after each use.